[MR imaging in congenital disorders of the brain]

MR imaging is an excellent tool for use in diagnosing congenital malformations of the brain. Such malformations cannot be reliably recognized or classified without an insight into the basic processes of the fetal development of the brain. Cortical malformations are classically divided into (1) malformations of neuronal proliferation, i.e. of stem cell proliferation in the periventricular germinal matrix zone, (2) disorders of neuronal migration, i.e. of the radial migration of the neurons from the periventricular germinal matrix zone to the cortical surface, and (3) disorders of cortical organization. Other cerebral malformations are agenesis or dysgenesis of the corpus callosum, encephaloceles, and various kinds of holoprosencephaly. Chiari malformation ans disorders on the Dandy-Walker spectrum are relatively common, primarily infratentorial disorders. Rarer infratentorial disorders are Joubert syndrome, rhombencephalosynapsis and Lhermitte Duclos syndrome.